L-Arginine is a semi-essential, cationic amino acid that serves as a key physiological precursor for the synthesis of nitric oxide (NO), a potent endogenous vasodilator. It plays a critical role in the urea cycle, protein synthesis, and the secretion of hormones like insulin, growth hormone, and prolactin. In the Indian context, it is widely used as a nutritional supplement and as adjunctive therapy in cardiovascular and metabolic conditions.
Adult: Oral: 500mg to 6g per day, divided into 2-3 doses. Common supplemental dose: 1-3g daily. For claudication: 2-3g twice or thrice daily. Must be taken with a glass of water.
Note: Take on an empty stomach or with a light meal for better absorption. Avoid taking with high-protein meals as competing amino acids can reduce uptake. Capsules/Tablets should be swallowed whole with a full glass of water. Do not crush or chew sustained-release formulations.
L-Arginine is the physiological substrate for endothelial nitric oxide synthase (eNOS). It is converted to nitric oxide (NO) and L-citrulline. NO then activates soluble guanylyl cyclase (sGC) in vascular smooth muscle cells, increasing intracellular cyclic guanosine monophosphate (cGMP). Elevated cGMP leads to dephosphorylation of myosin light chains, resulting in smooth muscle relaxation and vasodilation. This improves blood flow, reduces vascular resistance, and inhibits platelet aggregation.
Pregnancy: Category B: Animal reproduction studies have not shown risk, but no adequate, well-controlled studies in pregnant women. Use only if clearly needed, under medical supervision. Not recommended for routine supplementation.
Driving: May cause dizziness or hypotension, especially at initiation of therapy or with dose increases. Patients should be cautioned about operating machinery or driving until their response is known.
| Antihypertensive drugs (ACE inhibitors, ARBs, Nitrates, Calcium channel blockers) | Additive hypotensive effect; risk of severe hypotension. | Major |
| Phosphodiesterase-5 inhibitors (Sildenafil, Tadalafil) | Additive vasodilation and hypotensive effects. | Major |
| Potassium-sparing diuretics (Spironolactone, Amiloride) | Increased risk of hyperkalemia, especially with IV arginine. | Moderate |
| Lysine supplements | Competitive inhibition of intestinal absorption; may reduce efficacy of both. | Moderate |
| Insulin, Oral hypoglycemics | L-Arginine stimulates insulin secretion; may enhance hypoglycemic effect. | Moderate |
Same composition (L-Arginine (500mg)), different brands: